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Keywords = coherent synchrotron radiation

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17 pages, 2723 KB  
Article
Stitching Interferometry for X-Ray Mirror Metrology at the Hefei Advanced Light Facility (HALF)
by Yanghui Wang, Yifan Zhao, Huiyun Wang, Yiyang Hu, Liang He, Shuai Zhao and Xuewei Du
Photonics 2025, 12(11), 1106; https://doi.org/10.3390/photonics12111106 - 10 Nov 2025
Viewed by 919
Abstract
The advancements in the 4th-generation synchrotron radiation light sources, characterized by their enhanced coherence and brightness, have led to more stringent requirements for the surface quality of X-ray mirrors used in beamlines. This poses a significant challenge to the metrology of X-ray mirrors. [...] Read more.
The advancements in the 4th-generation synchrotron radiation light sources, characterized by their enhanced coherence and brightness, have led to more stringent requirements for the surface quality of X-ray mirrors used in beamlines. This poses a significant challenge to the metrology of X-ray mirrors. This research work focuses on high-precision measurement techniques for X-ray mirrors. The algorithmic principles of various stitching methods were introduced in detail, and a custom-built stitching measurement system was demonstrated. The system was used to perform a stitching measurement on an elliptical X-ray mirror, and the results showed high consistency with the data provided by JTEC. This verifies the effectiveness of the stitching interferometry method and the high measurement capability of our system. Full article
(This article belongs to the Special Issue Next-Generation X-Ray Optical Technologies and Applications)
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17 pages, 5508 KB  
Review
Application of Synchrotron Radiation in Fundamental Research and Clinical Medicine
by Chao Xiao, Jinde Zhang, Yang Li, Mingyuan Xie and Dongbai Sun
Biomedicines 2025, 13(6), 1419; https://doi.org/10.3390/biomedicines13061419 - 10 Jun 2025
Cited by 4 | Viewed by 2917
Abstract
Synchrotron radiation light sources have been successfully utilized in material science, biomedicine, and other fields due to their high intensity, excellent monochromaticity, coherence, and collimation. In recent years, synchrotron radiation has significantly expedited the advancement of medical applications, particularly through innovations in imaging [...] Read more.
Synchrotron radiation light sources have been successfully utilized in material science, biomedicine, and other fields due to their high intensity, excellent monochromaticity, coherence, and collimation. In recent years, synchrotron radiation has significantly expedited the advancement of medical applications, particularly through innovations in imaging and radiotherapy. For instance, synchrotron X-ray imaging has enabled high-contrast and spatial–temporal resolution images for early-stage diagnosis of breast cancer and cardiovascular diseases, offering superior diagnostic accuracy compared to conventional methods. Additionally, novel synchrotron radiation-based radiotherapy techniques, such as microbeam therapy and stereotactic radiotherapy, have shown great potential for clinical application by enabling precise tumor targeting while minimizing damage to surrounding healthy tissues. These advancements are projected to redefine imaging diagnostics and therapeutic strategies, particularly for resistant cancers, by offering enhanced precision, reduced radiation doses, and improved therapeutic outcomes. This review provides an overview of synchrotron radiation beamline characteristics, recent breakthroughs in imaging and radiotherapy, and their emerging applications in treating heart, breast, lung, bone, and brain conditions. Full article
(This article belongs to the Section Molecular and Translational Medicine)
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10 pages, 627 KB  
Article
Structural Insights into Phycocyanin Langmuir–Blodgett Multilayers via Serial Femtosecond Crystallography with X-ray Free-Electron Laser
by Eugenia Pechkova, Fabio Massimo Speranza, Paola Ghisellini, Stefano Fiordoro, Cristina Rando and Roberto Eggenhöffner
Crystals 2024, 14(9), 767; https://doi.org/10.3390/cryst14090767 - 29 Aug 2024
Viewed by 1784
Abstract
Serial femtosecond crystallography (SFX) with X-ray free-electron lasers (XFELs) has revolutionized classical X-ray diffraction experiments by utilizing ultra-short, intense, and coherent X-ray pulses. However, the SFX approach still requires thousands of nearly identical samples, leading to significant protein consumption. We propose utilizing Langmuir–Blodgett [...] Read more.
Serial femtosecond crystallography (SFX) with X-ray free-electron lasers (XFELs) has revolutionized classical X-ray diffraction experiments by utilizing ultra-short, intense, and coherent X-ray pulses. However, the SFX approach still requires thousands of nearly identical samples, leading to significant protein consumption. We propose utilizing Langmuir–Blodgett protein multilayers, which are characterized by long-range order, thermal stability, and the ability to induce protein crystallization, even in proteins that cannot be crystallized by conventional methods. This study aimed to combine the intrinsic properties of Langmuir–Blodgett multilayers with advanced XFEL techniques at the Linac Coherent Light Source. Since the macromolecule organization can be explored in nano or 2D crystals exploiting the properties of SFX–XFEL radiation that enable the capture of high-resolution diffraction images before radiation damage occurs, we propose Langmuir–Blodgett protein nanofilm technology as a novel approach for direct “on-chip” protein sample preparation. The present study extends previous investigations into Langmuir–Blodgett phycocyanin multilayer nanofilms using synchrotron radiation cryo-EM microscopy and second-order nonlinear imaging of chiral crystal (SONICC) experiments. We also examined the thermal stability of phycocyanin Langmuir–Blodgett multilayered films deposited on Si3N4 membranes to evaluate structural changes occurring at 150 °C compared with room temperature. Phycocyanin Langmuir–Blodgett films are worthy of investigation in view of their suitability for tissue engineering and other applications due to their thermal integrity and stability as the results of the present investigation reveal. Full article
(This article belongs to the Special Issue X-Ray Protein Crystallography)
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11 pages, 423 KB  
Article
Commissioning of Bunch Compressor to Compress Space Charge-Dominated Electron Beams for THz Applications
by Anusorn Lueangaramwong, Ekkachai Kongmon, Xiangkun Li, Prach Boonpornprasert, Georgi Georgiev, Mikhail Krasilnikov, Zakaria Aboulbanine, Gowri Adhikari, Namra Aftab, Matthias Gross, Raffael Niemczyk, Anne Oppelt, Houjun Qian, Christopher Richard, Grygorii Vashchenko, Tobias Weilbach and Frank Stephan
Appl. Sci. 2024, 14(5), 1982; https://doi.org/10.3390/app14051982 - 28 Feb 2024
Viewed by 1925
Abstract
The high peak current of the electron beam was found to be the key parameter for the THz SASE FEL at the Photo Injector Test facility at DESY in Zeuthen (PITZ). A multipurpose bunch compressor was implemented at PITZ to expand the parameter [...] Read more.
The high peak current of the electron beam was found to be the key parameter for the THz SASE FEL at the Photo Injector Test facility at DESY in Zeuthen (PITZ). A multipurpose bunch compressor was implemented at PITZ to expand the parameter space of proof-of-principle studies on the tunable high-power accelerator-based THz source for pump-probe experiments at the European XFEL. The magnetic chicane, consisting of four rectangular dipole magnets, is designed with a bending angle of 19 degrees, due to limited space in the PITZ original beamline, to compress electron bunches with a beam momentum of 15–20 MeV/c and a charge up to 2 nC. The space charge effect and coherent synchrotron radiation are expected to drastically affect the bunch compressor performance for these parameters, thereby challenging the beam transport throughout the bunch compressor. A staged commissioning strategy was developed in order to achieve optimum bunch compressor operation. The first commissioning procedure establishes electron beam transport throughout the reference path and provides minimum beam momentum dispersion after the bunch compressor. This procedure yielded correlations between dipole magnet currents. As a result, the first bunch compression experiments were performed. Full article
(This article belongs to the Special Issue Advanced Technologies of Particle Accelerators and Their Applications)
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10 pages, 4826 KB  
Article
X-ray 3D Imaging of Low-Density Laser-Target Materials
by Igor Artyukov, Natalia Borisenko, Gleb Burenkov, Alexander Eriskin, Maxim Polikarpov and Alexander Vinogradov
Photonics 2023, 10(8), 875; https://doi.org/10.3390/photonics10080875 - 28 Jul 2023
Cited by 8 | Viewed by 2325
Abstract
Achieving optimal design and precise control of the internal structure of laser-target materials are the primary objectives in various laser physics experiments, particularly in generating high flux photon and neutron beams. The study of low-density materials poses considerable challenges for X-ray analysis due [...] Read more.
Achieving optimal design and precise control of the internal structure of laser-target materials are the primary objectives in various laser physics experiments, particularly in generating high flux photon and neutron beams. The study of low-density materials poses considerable challenges for X-ray analysis due to their high transparency and minimal contrast. In this study, to obtain clear visualization of foams with sparse structures, we used phase-contrast X-ray tomography, utilizing a high-quality monochromatic X-ray beam from the synchrotron radiation source PETRA-III at DESY. Employing phase-contrast algorithms, the 3D structure of a foam-suspended glass microsphere inside the plastic cylinder was reconstructed with a level of image quality sufficient to visualize uniformity, displacement, and surface roughness on both sides of the microsphere. The primary focus of this investigation was a CH plastic capillary including 10 mg/cc CHO foam with a glass microsphere positioned at the center. The results of this study demonstrate that phase-contrast X-ray tomography with coherent synchrotron radiation is an effective and valuable technique for the development of new laser targets containing structured low-density materials. Full article
(This article belongs to the Special Issue Recent Advances in Optical Diffraction and Imaging)
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12 pages, 2997 KB  
Article
Tensile Microstrain Fluctuations in the BaPbO Units in Superconducting BaPb1−xBixO3 by Scanning Dispersive Micro-XANES
by Ruben Albertini, Salvatore Macis, Andrei A. Ivanov, Alexey P. Menushenkov, Alessandro Puri, Virginia Monteseguro, Boby Joseph, Wei Xu, Augusto Marcelli, Paula Giraldo-Gallo, Ian Randal Fisher, Antonio Bianconi and Gaetano Campi
Condens. Matter 2023, 8(3), 57; https://doi.org/10.3390/condmat8030057 - 11 Jul 2023
Cited by 4 | Viewed by 2739
Abstract
BaPb1−xBixO3 (BPBO) bismuthate, showing high TC superconductivity for 0.05 < x < 0.35, is an archetypal system for studying the complex inhomogeneity of perovskite lattice favoring the emergence of quantum coherence, called the superstripes phase. Local lattice [...] Read more.
BaPb1−xBixO3 (BPBO) bismuthate, showing high TC superconductivity for 0.05 < x < 0.35, is an archetypal system for studying the complex inhomogeneity of perovskite lattice favoring the emergence of quantum coherence, called the superstripes phase. Local lattice fluctuations, detected by EXAFS; nanoscale stripes, detected by electron microscopy; and two competing crystalline structures, detected by diffraction, are known to characterize the superconducting phase. At nanoscale [BaBiO3] centered nanoscale units (BBO) coexist with BaPbO3 centered (BPO) units in the BPBO perovskite; therefore, we expect a tensile microstrain in BPO units due the misfit strain between the two different lattices. Here, we report the measurement of the spatial micro-fluctuations of the local tensile microstrain ε in the BaPO units in superconducting Ba(Pb1−xBix)O3 crystals with x1 = 0.19 an x2 = 0.28. We show here the feasibility of applying the scanning dispersive micro-X-ray absorption near edge structure (SdμXANES) technique, using focused synchrotron radiation, to probe the microscale spatial fluctuations of the microstrain in BPO units. This unconventional real-space SdμXANES microscopy at the Pb L3 edge has been collected in the dispersive mode. Our experimental method allows us to measure either the local Bi chemical concentration x and the local lattice microstrain of local BBO and BPO units. The 5 × 5 micron-size spots from the focused X-ray beam allowed us to obtain maps of 1600 points covering an area of 200 × 200 microns. The mapping shows a substantial difference between the spatial fluctuations of the microstrain ε and the chemical inhomogeneity x. Moreover, we show the different relations ε(x) in samples with lower (x1 = 0.19) and higher (x2 = 0.28) doping respect to the optimum doping (x = 0.25). Full article
(This article belongs to the Section Superconductivity)
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12 pages, 3735 KB  
Article
Micro-Computed Tomography Beamline of the Australian Synchrotron: Micron-Size Spatial Resolution X-ray Imaging
by Benedicta D. Arhatari, Andrew W. Stevenson, Darren Thompson, Adam Walsh, Tom Fiala, Gary Ruben, Nader Afshar, Sinem Ozbilgen, Tingting Feng, Stephen Mudie and Prithi Tissa
Appl. Sci. 2023, 13(3), 1317; https://doi.org/10.3390/app13031317 - 18 Jan 2023
Cited by 16 | Viewed by 4105
Abstract
The first new beamline of the BRIGHT project—involving the construction of eight new beamlines at the Australian Synchrotron—is the Micro-Computed Tomography (MCT) beamline. MCT will extend the facility’s capability for higher spatial resolution X-ray-computed tomographic imaging allowing for commensurately smaller samples in comparison [...] Read more.
The first new beamline of the BRIGHT project—involving the construction of eight new beamlines at the Australian Synchrotron—is the Micro-Computed Tomography (MCT) beamline. MCT will extend the facility’s capability for higher spatial resolution X-ray-computed tomographic imaging allowing for commensurately smaller samples in comparison with the existing Imaging and Medical Beamline (IMBL). The source is a bending-magnet and it is operating in the X-ray energy range from 8 to 40 keV. The beamline provides important new capability for a range of biological and material-science applications. Several imaging modes will be offered such as various X-ray phase-contrast modalities (propagation-based, grating-based, and speckle-based), in addition to conventional absorption contrast. The unique properties of synchrotron radiation sources (high coherence, energy tunability, and high brightness) are predominantly well-suited for producing phase contrast data. An update on the progress of the MCT project in delivering high-spatial-resolution imaging (in the order of micron size) of mm-scale objects will be presented in detail with some imaging results from the hot-commissioning stage. Full article
(This article belongs to the Special Issue X-ray Medical and Biological Imaging)
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18 pages, 2781 KB  
Article
Compression of the Synchrotron Mössbauer X-ray Photon Waveform in an Oscillating Resonant Absorber
by Ilias R. Khairulin, Yevgeny V. Radeonychev and Olga Kocharovskaya
Photonics 2022, 9(11), 829; https://doi.org/10.3390/photonics9110829 - 4 Nov 2022
Cited by 2 | Viewed by 1961
Abstract
A technique to transform the waveform of a 14.4 keV photon (time dependence of the photon detection probability or, equivalently, the intensity of the single-photon wave packet) into a regular sequence of short, nearly bandwidth-limited pulses with a controlled number of pulses is [...] Read more.
A technique to transform the waveform of a 14.4 keV photon (time dependence of the photon detection probability or, equivalently, the intensity of the single-photon wave packet) into a regular sequence of short, nearly bandwidth-limited pulses with a controlled number of pulses is proposed. It is based on coherent forward scattering of single X-ray photons from a synchrotron Mössbauer source (SMS) in an optically thick, vibrating, recoilless 57Fe resonant absorber. The possibility of compressing the waveform of an SMS photon into a single short bell-shaped pulse is predicted. The experiment is proposed for compressing a 100 ns duration 14.4 keV single-photon wave packet produced by SMS at the European Synchrotron Radiation Facility (ESRF) into a single bell-shaped pulse of less than 20 ns duration and more than twice the peak intensity. Such single-photon coherent pulses are promising for applications in the fast-developing field of X-ray quantum optics, including possible implementation of quantum memory. Full article
(This article belongs to the Special Issue Advances in X-ray Optics)
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19 pages, 2377 KB  
Review
Early Days of SACLA XFEL
by Tetsuya Ishikawa
Photonics 2022, 9(5), 357; https://doi.org/10.3390/photonics9050357 - 18 May 2022
Cited by 1 | Viewed by 5063
Abstract
The SACLA (SPring-8 Angstrom compact laser) was designed to significantly downsize the SASE (self-amplified spontaneous emission) type XFEL (X-ray free-electron laser), in order to generate coherent light in the wavelength region of 0.1 nm by adopting an in-vacuum undulator that can shorten the [...] Read more.
The SACLA (SPring-8 Angstrom compact laser) was designed to significantly downsize the SASE (self-amplified spontaneous emission) type XFEL (X-ray free-electron laser), in order to generate coherent light in the wavelength region of 0.1 nm by adopting an in-vacuum undulator that can shorten the magnetic field period length. In addition, a SASE XFEL facility with a total length of 700 m has become a reality by using a C-band RF accelerating tube that enables a high acceleration gradient. Although progress was initially slow, the small-scale, low-cost SACLA was smoothly constructed, and it became the second light source to lase in the 0.1 nm wavelength region, following the LCLS (linac coherent light source) in the United States. In this paper, we look back on the history leading up to SACLA. and describe the SCSS (SPring-8 compact SASE source) project as a preparatory stage and a part of the construction/commissioning of SACLA. Since March 2012, SACLA has been operating as a shared user facility. Just a few of the upgrade activities of the facility and advanced research conducted are introduced. Finally, we will discuss the future development of the SPring-8 site, which has co-located the third-generation synchrotron radiation facility SPring-8 and the X-ray free-electron laser facility SACLA. Full article
(This article belongs to the Special Issue XUV and X-ray Free-Electron Lasers and Applications)
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25 pages, 3846 KB  
Review
X-ray Diffraction Imaging of Deformations in Thin Films and Nano-Objects
by Olivier Thomas, Stéphane Labat, Thomas Cornelius and Marie-Ingrid Richard
Nanomaterials 2022, 12(8), 1363; https://doi.org/10.3390/nano12081363 - 15 Apr 2022
Cited by 4 | Viewed by 4783
Abstract
The quantification and localization of elastic strains and defects in crystals are necessary to control and predict the functioning of materials. The X-ray imaging of strains has made very impressive progress in recent years. On the one hand, progress in optical elements for [...] Read more.
The quantification and localization of elastic strains and defects in crystals are necessary to control and predict the functioning of materials. The X-ray imaging of strains has made very impressive progress in recent years. On the one hand, progress in optical elements for focusing X-rays now makes it possible to carry out X-ray diffraction mapping with a resolution in the 50–100 nm range, while lensless imaging techniques reach a typical resolution of 5–10 nm. This continuous evolution is also a consequence of the development of new two-dimensional detectors with hybrid pixels whose dynamics, reading speed and low noise level have revolutionized measurement strategies. In addition, a new accelerator ring concept (HMBA network: hybrid multi-bend achromat lattice) is allowing a very significant increase (a factor of 100) in the brilliance and coherent flux of synchrotron radiation facilities, thanks to the reduction in the horizontal size of the source. This review is intended as a progress report in a rapidly evolving field. The next ten years should allow the emergence of three-dimensional imaging methods of strains that are fast enough to follow, in situ, the evolution of a material under stress or during a transition. Handling massive amounts of data will not be the least of the challenges. Full article
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11 pages, 2184 KB  
Article
Terahertz Imaging for Formalin Fixed Malignant Liver Tumors Using Two-Band Beamline at the Accelerator Facility of Nihon University
by Yusuke Kawashima, Suemitsu Masaaki, Kayo Kuyama, Takeshi Sakai, Yasushi Hayakawa, Takashi Kaneda and Norihiro Sei
Appl. Sci. 2022, 12(4), 2229; https://doi.org/10.3390/app12042229 - 21 Feb 2022
Cited by 5 | Viewed by 3214
Abstract
We investigated the transmission characteristics of formalin fixed human liver samples in which normal liver tissue and malignant liver tumor were mixed using terahertz (THz) coherent synchrotron radiation at an infrared free-electron laser (FEL) facility at Nihon University. Infrared-FEL imaging has indicated that [...] Read more.
We investigated the transmission characteristics of formalin fixed human liver samples in which normal liver tissue and malignant liver tumor were mixed using terahertz (THz) coherent synchrotron radiation at an infrared free-electron laser (FEL) facility at Nihon University. Infrared-FEL imaging has indicated that the amount of water molecules in the tumor tissue is not different from that in the normal tissue. However, the transmission of the incipient tumor tissue was lower than that of the normal tissue in THz imaging because the tumor tissue contained more water molecular clusters than the normal tissue. The tumor tissue became more permeable owing to the development of fibrous tissue around it. THz imaging will be more useful for discriminating liver tissues by increasing the spatial resolution. Full article
(This article belongs to the Topic Medical Image Analysis)
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33 pages, 15001 KB  
Review
From Femtoseconds to Hours—Measuring Dynamics over 18 Orders of Magnitude with Coherent X-rays
by Felix Lehmkühler, Wojciech Roseker and Gerhard Grübel
Appl. Sci. 2021, 11(13), 6179; https://doi.org/10.3390/app11136179 - 2 Jul 2021
Cited by 66 | Viewed by 9673
Abstract
X-ray photon correlation spectroscopy (XPCS) enables the study of sample dynamics between micrometer and atomic length scales. As a coherent scattering technique, it benefits from the increased brilliance of the next-generation synchrotron radiation and Free-Electron Laser (FEL) sources. In this article, we will [...] Read more.
X-ray photon correlation spectroscopy (XPCS) enables the study of sample dynamics between micrometer and atomic length scales. As a coherent scattering technique, it benefits from the increased brilliance of the next-generation synchrotron radiation and Free-Electron Laser (FEL) sources. In this article, we will introduce the XPCS concepts and review the latest developments of XPCS with special attention on the extension of accessible time scales to sub-μs and the application of XPCS at FELs. Furthermore, we will discuss future opportunities of XPCS and the related technique X-ray speckle visibility spectroscopy (XSVS) at new X-ray sources. Due to its particular signal-to-noise ratio, the time scales accessible by XPCS scale with the square of the coherent flux, allowing to dramatically extend its applications. This will soon enable studies over more than 18 orders of magnitude in time by XPCS and XSVS. Full article
(This article belongs to the Special Issue Trends in Sub-Microsecond X-ray Science with Coherent Beams)
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7 pages, 218 KB  
Editorial
Terahertz as a Frontier Area for Science and Technology
by Akinori Irizawa, Stefano Lupi and Augusto Marcelli
Condens. Matter 2021, 6(3), 23; https://doi.org/10.3390/condmat6030023 - 28 Jun 2021
Cited by 10 | Viewed by 4398
Abstract
Recent theoretical and experimental research is triggering interest to technologies based on radiation in the region from ~0.1 to 20 Terahertz (THz). Today, this region of the electromagnetic (e.m.) spectrum is a frontier area for research in many disciplines. The technological roadmap of [...] Read more.
Recent theoretical and experimental research is triggering interest to technologies based on radiation in the region from ~0.1 to 20 Terahertz (THz). Today, this region of the electromagnetic (e.m.) spectrum is a frontier area for research in many disciplines. The technological roadmap of the THz radiation considers outdoor and indoor communications, security, drug detection, biometrics, food quality control, agriculture, medicine, semiconductors, and air pollution, and demands high-power and sub-ps compact sources, modern detectors, and new integrated systems. There are still many open questions regarding working at THz frequencies and with THz radiation. In particular, we need to invest in new methodologies and in materials exhibiting the unusual or exotic properties of THz. This book contains original papers dealing with some emerging THz applications, new devices, sources and detectors, and materials with advanced properties for applications in biomedicine, cultural heritage, technology, and space. Full article
13 pages, 3685 KB  
Article
X-ray Phase-Contrast Computed Tomography for Soft Tissue Imaging at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron
by Benedicta D. Arhatari, Andrew W. Stevenson, Brian Abbey, Yakov I. Nesterets, Anton Maksimenko, Christopher J. Hall, Darren Thompson, Sheridan C. Mayo, Tom Fiala, Harry M. Quiney, Seyedamir T. Taba, Sarah J. Lewis, Patrick C. Brennan, Matthew Dimmock, Daniel Häusermann and Timur E. Gureyev
Appl. Sci. 2021, 11(9), 4120; https://doi.org/10.3390/app11094120 - 30 Apr 2021
Cited by 25 | Viewed by 5469
Abstract
The Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential [...] Read more.
The Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential for a range of biomedical X-ray applications, including radiotherapy and medical imaging experiments. One of the imaging modalities available at IMBL is propagation-based X-ray phase-contrast computed tomography (PCT). PCT produces superior results when imaging low-density materials such as soft tissue (e.g., breast mastectomies) and has the potential to be developed into a valuable medical imaging tool. We anticipate that PCT will be utilized for medical breast imaging in the near future with the advantage that it could provide better contrast than conventional X-ray absorption imaging. The unique properties of synchrotron X-ray sources such as high coherence, energy tunability, and high brightness are particularly well-suited for generating PCT data using very short exposure times on the order of less than 1 min. The coherence of synchrotron radiation allows for phase-contrast imaging with superior sensitivity to small differences in soft-tissue density. Here we also compare the results of PCT using two different detectors, as these unique source characteristics need to be complemented with a highly efficient detector. Moreover, the application of phase retrieval for PCT image reconstruction enables the use of noisier images, potentially significantly reducing the total dose received by patients during acquisition. This work is part of ongoing research into innovative tomographic methods aimed at the introduction of 3D X-ray medical imaging at the IMBL to improve the detection and diagnosis of breast cancer. Major progress in this area at the IMBL includes the characterization of a large number of mastectomy samples, both normal and cancerous, which have been scanned at clinically acceptable radiation dose levels and evaluated by expert radiologists with respect to both image quality and cancer diagnosis. Full article
(This article belongs to the Special Issue X-ray Medical and Biological Imaging)
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30 pages, 400 KB  
Review
Emission Mechanisms of Fast Radio Bursts
by Yuri Lyubarsky
Universe 2021, 7(3), 56; https://doi.org/10.3390/universe7030056 - 4 Mar 2021
Cited by 98 | Viewed by 6507
Abstract
Fast radio bursts (FRBs) are recently discovered mysterious single pulses of radio emission, mostly coming from cosmological distances (∼1 Gpc). Their short duration, ∼1 ms, and large luminosity demonstrate coherent emission. I review the basic physics of coherent emission mechanisms proposed for FRBs. [...] Read more.
Fast radio bursts (FRBs) are recently discovered mysterious single pulses of radio emission, mostly coming from cosmological distances (∼1 Gpc). Their short duration, ∼1 ms, and large luminosity demonstrate coherent emission. I review the basic physics of coherent emission mechanisms proposed for FRBs. In particular, I discuss the curvature emission of bunches, the synchrotron maser, and the emission of radio waves by variable currents during magnetic reconnection. Special attention is paid to magnetar flares as the most promising sources of FRBs. Non-linear effects are outlined that could place bounds on the power of the outgoing radiation. Full article
(This article belongs to the Special Issue Fast Radio Bursts)
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